Answer is the 2nd option. PET activity and therefore PET sensitivity is very low in diffuse type or signet ring carcinoma. In a retrospective analysis of both the authors’ own patients along with a systematic literature review (Kaneko et al., J Nucl Med 2015), significant predictors of 18F-FDG avidity were noted to include non–signet ring cell carcinoma type, large tumor size, and glucose transporter 1–positive expression on immunohistochemistry.
Upon review of the outside pathology, our patient was confirmed to have ductal (rather than lobular) carcinoma of the breast and lacked CDH1 germline mutations on genetic panel testing.
How might clinical management and surgical approach be affected if our patient was diagnosed with CDH1 mutated hereditary gastric cancer?